The present application is directed to the measurement of material on the surface of an object, and more particularly, to the measuring of the amount of a substance on a wire, such as automatic welding wire.
To improve the welding process, the welding wire has a thin substance layer applied to its surface. The substance layer may be a lubricant such as oil. The amount of lubricant on the welding wire is known to have a direct impact on the overall welding process, and the amount and type can vary dependent on a variety of parameters including the type of wire, the type of welding process, as well as the material which is to be welded. The surface of the welding wire may also carry contaminants or residuals from the wire forming process. As shown in FIG. 1, uncoiled drawn welding wire 10, which has been drawn down to its final size, is passed through an applicator 12, which applies a layer of oil 14 or other lubricant to the outer surface of welding wire 10.
It has been noted above that lubrication of welding wire is beneficial in the welding process. In particular, oil or other lubricants provide at least two functions. In an automatic welding environment, the welding wire is automatically fed through a cable into a gun or torch. The cable may be of a significant length, therefore oil or other lubricant is used to lubricate the cable assembly as the wire is pushed through the cable to the gun or torch during the welding process. Additionally at times, stabilizers are used with the oil or lubricant for a smoother welding process.
To gain the benefit of the oil or lubricant application process, certain specifications need to be met. For example, an appropriate amount of oil or lubricant must be on the surface. Additionally, other specifications may permit only a certain amount of contaminants, or certain levels of additives or residual from the wire forming process. Testing is therefore undertaken to determine whether the oil, lubricant, additives, contaminants or residual material on the surface of the wire are within specifications determined to be desirable for a particular wire. Presently, the primary technique for performing the measurements, is by a crude weight loss technique. This technique can only be undertaken after the wire manufacturing process has been completed, and thus only provides results for a small fraction of the wire produced. The technique is also non-specific to the oil or lubricant, and is subject to errors resulting from sample preparation or the presence of other materials removed during the test.
Once the wire has been drawn and oiled, it is wound in large coils, such as coil 16 of FIG. 2, which may have thousands of feet of the drawn and oiled wire. The present testing process requires someone to unwind a portion of the coiled wire and either inspect a portion of the wire, including measuring the amount of oil on the surface, and/or taking a sample of the oil to thereafter measure characteristics of the oil such as the viscosity, oil composition, contaminants or other substances.
If this testing determines the oil is out of specification, additional wire is unwrapped from the coil and further testing is undertaken. In some situations, it may be necessary to unwrap the coil a number of times, peeling off 100 to 200 pounds of wire to perform these tests. This process goes on until the tested oil or lubricant is found to be within specification.
The foregoing testing procedure is cumbersome and tedious, as well as inefficient. Additionally, it is possible that during the application of the oil or other lubricant, the application process may go in and out of specification. Therefore, even if it is determined a portion of the wire is within specification, at a point further back on the coil the application process may have been out of specification, so there is no assurance the entire coil is within specification.
In consideration of the above, it is desirable to provide a method and system for measuring the amount of surface material on a wire, which permits for a faster, and more accurate measurement.